The present invention relates to a lens barrel and a photographing apparatus.
In recent years, as personal computers have become more widely used, digital cameras in which images can be easily taken in to personal computers have also become widespread. In addition, it is becoming commonplace for digital cameras to be incorporated into information processing devices such as mobile computers, cellular phones, and personal digital assistants (PDA). As digital cameras have become more widespread, there has been a desire for more compact digital cameras, and the lens unit needs to be even more compact. There is also a demand for a high magnification zoom lens and a zooming mechanism that can be used with the high magnification zoom lens is needed.
Therefore, to make the lens unit compact, as an example of storing telescopically the barrel for holding the lens, there is a mechanism for restricting the posture of a movable frame moving back and forth along a straight line, which is a posture restriction mechanism for the movable frame including a first shaft orthogonal to the straight line, a second shaft orthogonal to both the straight line and the first shaft for restricting the posture of the movable frame, a first holding mechanism, during movement of the movable frame, for holding the first shaft and keeping the orthogonal posture of the first shaft to the straight line, and a second holding mechanism for holding the second shaft and keeping the orthogonal posture of the second shaft to the first shaft, wherein the first holding mechanism and second holding mechanism respectively have either of a cam mechanism including the first shaft and second shaft and an inverse cam mechanism (refer to Unexamined Japanese Patent Application Publication No. 11-119078).
In addition, there is a camera in which the lens barrel is formed from three units which include the stationary barrel which forms a portion of the camera body; the middle barrel which is stored telescopically inside the stationary barrel; and the movable barrel which is also stored telescopically inside the middle barrel, and the inner surface of the stationary barrel has a two-group type zoom device on which a helicoid groove is formed. More specifically, the engagement portion provided on the end portion of the middle barrel is engaged with the helicoid groove. The middle barrel can rotate in both normal and reverse directions via a gear mechanism using a direct current motor, and it moves telescopically with respect to the stationary barrel by the rotation. Further, the helicoid grooves are also formed on the inner surface of the middle barrel and the engagement portion of the end portion of the movable barrel engages with the helicoid grooves. The movable barrel cannot rotate with respect to the stationary barrel and thus when the middle barrel is rotated, it moves telescopically in the same direction as the telescopic movement of the middle barrel (See Unexamined Japanese Patent Application Publication No. 06-324247).
It is to be noted that the lens barrel is telescopically stored and the state of being stored inside the camera body is called collapsed.
However, in the posture restraining mechanism of the movable frame described in Unexamined Japanese Patent Application Publication No. 11-119078, a structure is described in which one movable frame can move with respect to the stationary main frame, but in order to be usable with the high magnification zoom lens of recent years, it is necessary, for example, to increase the length of the arm portion in order to match the zooming mechanism which moves the zoom lens group toward the object side in large dimensions that is closest to the object of the zoom lens and it thus difficult for the length of the arm to be made compact corresponding to the reduced size of the zoom lens. Moreover, there is no disclosure with regard to two or more movable frames.
In addition, the two-group type zooming device described in Unexamined Japanese Patent Application Publication No. 06-324247, is a three unit structure, but it is necessary to form helicoid grooves on the inner surface of the stationary barrel and the middle barrel, and it is also necessary to form helicoid grooves on the end outer surface of the middle barrel and the end outer surface of the movable barrel which engage with these, and thus the mechanism becomes complex. Further, the barrels must be cylindrical because they have helicoid grooves. For this reason, the lens barrel which should correspond to the reduced size resulting from recent zoom lens cannot be made square to match the square shape of the image pickup element.
The present invention was conceived in view of the foregoing and an object thereof is to provide lens barrel which has a compact multilevel collapsing is possible with a simple structure and a photographing apparatus which comprises this lens barrel.